Lincoln New York. Might work later on sideview. It is supposedly an executive limo. Currently I am working on a new yaw control for jet exhaust on airplanes. if aspect ratio is still an issue, let me know.

1. Principle of continuity. Lines tend to continue, even if they are disrupted by windows , wheel arches or stampings and facets.
2.Paralelness. Lines tend to go paralel to each other, irregardless of their size or function.
3. Symmety to an imagined axis. Lines tend to have a mirror effect, being symmetrical to each other. Symmetry can be at any angle or disposition.
4.90 degree tendency. Lines tend to reach straight line when meeting at abrupt angles. Lines can`t always meet 90 degree angle, but they tend towards it.
5. External curves don`t tolerate less than 90 degree angle when facets break outward.(For example- hood line and the hood slope down.)
Gravitational lensing. Objects of mass tend to distort the shape of nearby object finding an equilibrium of shape between the both.
6.Visual mass. Objects, especially cars tend to have visual mass, which itself tends to find definite proportions to the rest of the object.
7. Slope of mass. Every car tends to be sloping either forward or backward. it can be compared to a wave in ocean - it is the direction towards which the tension is released.
8.Area of tranquility. An area in a car where no significant design curvature or bending takes place. It is for your eyes to relax. Side of a car must have this area. Should occupy no less than a third of total side area.
9. External surfaces( bulge outwards) always tolerate bigger curvatures than negative curvatures( bulge inwards, indentation).
10.Front overhang versus rear overhang. Front overhang as compared to rear should be in vicinity 1 to 3 up to 3 to 1, but not more.
11. Wheel arch width and disposition.You should find equilibrium by being able to put between 2,5 to 3,5 widths of tyres between rear and front tyres( sideview). It doesn`t apply to heavy machinery.
12.Main object of interest. There should be a central , the most massive element of design, which your eyes can get focused on. for the main object of interest a seperate visual mass is suggested, for example for headlights.
13. Car height versus window height. You should be able to put no more than 3 heights of a side window at its tallest point under the window to the curvature of the car where the facet bends underneath the car( sideskirt level).
14. The principle of moderate waving. The longer the line, the more fragile it becomes, and waves more moderately.Short lines can be abrupt and curved at any amount or angle.
15. principle of practicality. All cars are designed accordingly to human body functions and abilities, such as door handle size is dependent on the power applicable to open them, to the shape of hand,average height of a person etc; Door size is designed so that a person can enter it, etc.
16. The principle of dynamism. Dynamique of a design is achieved by distortion. Distortion of symmetry, paralelness or perspective.

I will try to develop my design language within my own principles, so I put them here so I could check them from now and then. Thanks:0

Lincoln New York. Might work later on sideview. It is supposedly an executive limo. Currently I am working on a new yaw control for jet exhaust on airplanes. if aspect ratio is still an issue, let me know.

The roofline is too narrow at the top. Here is a chrysler 300 from the front.

On the G9. Its still a bit off. Maybe dont do such a traditional iso view.

The only comment I would like to give, is that your renderings feels quite smudgy. I recommend you to take a good look at some professionals' car renderings to learn more about how to create a proper car rendering, understanding light and reflection.
Try the tutorials on CarBodyDesign.com
If you do the reflections/renderings right, then your sketches might look much more better.
Other than that, I think you really enjoy playing with forms and proportion, which I believe is a very important exercise.
Also using ellipse tools for the wheels is a smart trick to make it look right.
Keep it up!